Phase II clinical trials with time-to-event endpoints: optimal two-stage designs with one-sample log-rank test

Phase II clinical trials are often conducted to determine whether a new treatment is sufficiently promising to warrant a major controlled clinical evaluation against a standard therapy. We consider single‐arm phase II clinical trials with right censored survival time responses where the ordinary one‐sample logrank test is commonly used for testing the treatment efficacy. For planning such clinical trials, this paper presents two‐stage designs that are optimal in the sense that the expected sample size is minimized if the new regimen has low efficacy subject to constraints of the type I and type II errors. Two‐stage designs, which minimize the maximal sample size, are also determined. Optimal and minimax designs for a range of design parameters are tabulated along with examples. Copyright © 2013 John Wiley & Sons, Ltd.